Abstract
An 80-year-old man was admitted withright pleural effusion and bilateral axillary lymph node enlargement. Histopathological examination of the axillary lymph node biopsy specimen showed diffuse large B-cell lymphoma (DLBCL). The pleural effusion was exudative and predominantly lymphocytic, and cytology of the effusion was compatible with malignant lymphoma. Although acid-fast bacillus smear and polymerase chain reaction analysis of the pleural effusion were negative, pleural adenosine deaminase (P-ADA) was high (79.2 IU/L). We suspected tuberculous pleurisy and performed thoracoscopy. We diagnosed DLBCL with tuberculous pleurisy and started tuberculosis treatment. When P-ADA is high, thoracoscopy should be performed to explore tuberculous pleurisy.